The present invention relates to a valve for use in a sludge pump system. The valve is used in pumping systems, generally in combination with a displacement pump.
The pumping systems are used to transfer aggressive, abrasive and corrosive liquids containing granular material such as sand, coal, ore, found, for example, in mining waste. These liquids are frequently pumped over long distances, often at high temperatures, and under high pressures. Such conditions place extremely high demands on the durability of the pumping systems components including the valve.
Dutch Patent Application No. 8600545 describes a valve for use in a pumping system with a metal to metal contact surface, partially with a metal to elastic material contact surface. The metal to elastic material contact surface allows sludge material, which is present between the contact surfaces when the valve closes, and, as a result, is under extra high pressure, to escape via grooves provided in the metal contact without causing damage to the valve. The use of elastic sealing rings under the conditions described above, creates new problems, as are mentioned in the Dutch Patent Application. In use, the elastic material wears very quickly, thereby failing in its intended function. The result is that the elastic sealing rings must constantly be replaced. This results in shut down of the system, with the attendant consequences, such as cost, etc. Attempts have been made to avoid replacing the sealing rings by using symmetrical rings. Thus, the rings which were worn on one side could be reversed and reused. However, even this approach has not been fully successful and there has been a considerable decline in the use of elastic sealing rings.